A 13.56 MHz pulse-width modulation active rectifier for implantable medical devices

In this paper, a 13.56 MHz regulated dual-output active rectifier is proposed for implantable medical devices (IMDs). By adopting the pulse-width modulation (PWM) to control the conduction time of the rectifying switches, the proposed active rectifier is able to realize the rectification and regulation of dual-output voltages without adding DC-DC converters. The proposed automatic digital offset compensation (ADOC) can automatically compensate both turn-on and turn-off delay to maximize the conversion power and minimize the reverse current. Dual-output voltages 1.8 V and 3.3 V are generated to supply the internal circuit in IMDs. The simulated maximum power conversion efficiency (PCE) is 78.5%, and the input operating voltage ranges from 3.6 V to 5 V. Comparing to the conventional constant offset calibration, the efficiency improvement of 8% is obtained.